The primary objective of this study is to identify the morphological basis of altered pulmonary mechanics in early chronic obstructive pulmonary disease (COPD) and to contrast these changes with those of normal maturation and aging. Studies are performed on highly selected lungs from victims of sudden, non-hospital death to minimize possible effects of edema and inflammation. The population includes normal lungs over a wide age range and a significant number morphological changes of early COPD. Lung mechanics measurements include static compliance, dynamic compliance, pulmonary resistance, and flow-volume plots. The validity of these measurements compared to living subjects has been confirmed in preliminary studies. Morphometric measurements include central airways diameter, membranous bronchiole diameter, the proportion of bronchial mucous gland, and mean linear intercept. Quantitative measurements will also be made of the capillary bed, muscular arteries, and the elastin fiber network. These studies will provide anatomical information to interpret changes in pulmonary mechanics in early COPD and provide insight concerning the role of aging and disease on changes in the elastin fiber network, the capillaries, and the small airways.